This invention relates to an apparatus and method for setting electronic components into printed circuit boards (PCB), and in particular, is directed towards an assembly station which includes a pair of stacked support tables for holding the component parts used in the assembly of the boards, and an illuminated work area for shining light through a series of frames of a programmable mask which is sequentially transported across the work area in synchronization with the movement of the support tables.
As is well known, printed circuit boards usually are arranged to receive a variety of electronic components. Each individual circuit board is provided with perforations where the lead or terminal wires of various components are passed through from one side of the board to the other, the leads being connected to the circuit of the board on the latter side. Since the different types of components are closely spaced on the printed circuit board, the openings for the component lead wires are likewise closely spaced, and present a confusing array that makes it a difficult and slow process to set the components into the board with their lead wires extending through the proper perforations intended for them. In the past, great skill and knowledge on the part of the board assembler was required, which added substantial cost to the printed circuit board product.
A number of prior art devices are known which attempt to reduce the time and cost of printed circuit board assembly. For example, the U.S. patent to Chamillard et al, U.S. Pat. No. 3,667,104, issued June 6, 1972, discloses a printed circuit board assembly station which includes a rotary parts bin synchronously operated in conjunction with a plurality of selectably lightable lamps for sequentially back lighting different hole positions of a printed circuit board for disclosing the particular locations at which a particular bin component is to be mounted. Feldman et al, U.S. Pat. No. 3,621,554, issued Nov. 23, 1971, shows the use of a movable piano player roll-type mask having a plurality of openings in it, through which light is directed to corresponding holes of a circuit board for indicating the component insertion location positions. A similar device employing a fixed mask is disclosed in the U.S. patent to Howie, U.S. Pat. No. 3,372,455, issued Mar. 12, 1968. The U.S. patent to Savitt, U.S. Pat. No. 2,959,848, issued Nov. 15, 1960, also shows an optical assembling station including an apertured platform means which is backlighted through a mask to indicate color coded hole positions on a circuit board.
Rotary assemblies for delivering parts in conjunction with an indicated insertion sequence also are known in the art. The U.S. patents to Cronkite et al, U.S. Pat. No. 3,250,992, issued May 10, 1966; Hubbard, U.S. Pat. No. 3,548,493, issued Dec. 22, 1970; Leonhardt et al, U.S. Pat. No. 3,711,926, issued Jan. 23, 1973; Hall et al, U.S. Pat. No. 3,731,363, issued May 4, 1973; Ragard, U.S. Pat. No. 3,852,865, issued Dec. 10, 1974; and Ragard et al, U.S. Pat. No. 3,859,707, issued Jan. 14, 1975, all disclose rotary apparatus for presenting parts to an assembler.
Other art dealing with analogous subject matter includes the U.S. patents to Gray, U.S. Pat. No. 3,169,305, issued Feb. 16, 1965; Knoll et al, U.S. Pat. No. 3,564,692, issued Feb. 23, 1971; Sauve et al, U.S. Pat. No. 3,619,886, issued Nov. 16, 1971; Frels et al, U.S. Pat. No. 3,611,544, issued Oct. 12, 1971; Kowalski, U.S. Pat. No. 3,760,484, issued Sept. 25, 1973; Feldman, U.S. Pat. No. 3,815,204, issued June 11, 1974; and Holiday, U.S. Pat. No. 3,831,250, issued Aug. 27, 1974.
While these prior art apparatus work well for their intended purposes, their very number and diversity indicate that problems inherent in printed circuit board construction heretofore have not been resolved to the satisfaction of those involved in printed circuit board manufacture.
Our apparatus simplifies printed circuit board construction by permitting the coordination at a single station of a number of input functions, individual ones of which may be accomplished separately at a number of remote locations. Thus, a mask for use in the apparatus of this invention is programmed at an independent location by dividing the mask into a plurality of frames indicating the sequential insertion of electronic components within the corresponding printed circuit board. Each frame is numbered and includes position indicators on the mask for locating the particular frame with respect to the circuit board or boards under construction. The position indicators permit the mask to be used in conjunction with any assembly station of our invention. Alignment problems between the mask and circuit boards under construction inherent in prior art devices, are eliminated, as each frame automatically is located correctly by the position indicators, regardless of errors resulting from manufacturing tolerances between the programming station and the assembly station, or for errors arising because of differences in roll size and frame location on the roll. That is to say, automatic frame advancement is possible because frame location at the assembly station is a determination made autonomously of mask manufacturing considerations, although location markings are made during mask construction. Preferably, timing indicators also are made on the mask which enables the apparatus of our invention to advance the mask to the succeeding frame after the termination of a predetermined elapsed time period corresponding to the idealized time required for component insertion. Components required for insertion in the respective frames of the mask may be prepared remotely and placed in a plurality of part trays or bins which are arranged and stored according to frame sequence on the mask. The tray plurality may be sent directly to the assembly station or stored for later use. That is, all components required for a construction program set out on a particular mask may be arranged in a single storage and transporting package and correlated with the mask at the assembly station at a later time.
The apparatus or device disclosed herein includes an illuminated work area over which the mask is drawn. Means are provided for positioning each frame of the mask on the work area. A number of specific structural features are incorporated which enable the apparatus of our invention to coordinate frame and part presentation to the operator, and to time the operations required by each frame of the mask. Part presentation is accomplished through a unique arrangement of rotatable storage tables which receive the parts trays in sequential order. The parts trays are presented to the operator so that only the electrical component required for board insertion in a particular frame is available to the operator. Consequently, relatively fool-proof assembly results, in that single components and component location are presented to the operator simultaneously. The number of frames available for use with coordinated part presentation normally is sufficient to complete most printed circuit board constructions.
One of the objects of this invention is to provide an apparatus which simplifies assembly of printed circuit boards.
Another object of this invention is to provide an apparatus which coordinates part selection and part location during assembly of printed circuit boards.
Yet another object of this invention is to provide an apparatus with improved location capabilities for positioning a mask with respect to the printed circuit board under construction.
Another object of this invention is to provide an assembly apparatus utilizing a transferrable mask which incorporates a timing function indicating idealized time for component placement.
Still another object of this invention is to provide a simplified method for constructing a printed circuit board.
Other objects of this invention will be apparent to those skilled in the art in light of the following description and accompanying drawings.